Two killers (Boardwalk Empire’s Michael Pitt and Michael Stuhlbarg) are debating the niceties of their next job — whether or not their victim should be shot in the eyeball — when a third figure, dressed in a Mexican wrestling mask, walks up and BLAM!, blows them both away. This is the opening scene of Martin McDonagh’s second feature (after the 2008 In Bruges) about lowlife characters unfortunate enough to encounter murderers even more deranged than they. It’s an old-fashioned John Huston caper film extended to sulfurous comedy — from Beat the Devil to Meet the Devil.

Since its world premiere in the Midnight Madness section of last month’s Toronto Film Festival, Seven Psychopaths has acquired a cult patina, not just from its own trailer but also from an all-feline parody for a film called Seven Psychocats. That one might convince the 42-year-old McDonagh he’d finally made the big time. An award-winning playwright since his mid-twenties, with his 1996 The Beauty Queen of Leenane, he turned to the stage only after studios had rejected all his film scripts. In 1998, for a TIME story called “When O’Casey Met Scorsese,” he told our theater critic Richard Zoglin, “I want to write plays … that a film fan would be interested in seeing, like the new De Niro movie.”

Instead, in Seven Psychopaths, he assembles a killer cast of Colin Farrell, Sam Rockwell, Woody Harrelson, Christopher Walken and many other weird worthies for a Tarantinish crime comedy full of McDonagh’s trademark quirky-menacing stage conversation (“Talking!?” Rockwell says in annoyed astonishment; “What is this, a f—ing French movie?”) and to pursue the author’s favorite truism that life is even stranger, funnier and more painful than death. McDonagh’s plays — most of them set in his ancestral Galway, and dealing with family animosities that escalate to Armageddon level — don’t exactly mix the horrifying and the hilarious; they are both at once, evoking laughs that might be gasps.

Except for A Behanding in Spokane, whose main character did lose an extremity when hooligans tied it to a roailroad track and let a train sever it, McDonagh’s plays tend to be remembered not by their titles but by their graphic incidents. A Skull in Connemara is the one about the corpse with a gashed cranium; The Pillowman is the one about the fairy tales that inspire a child molester; The Lieutenant of Inishmore is the one with the dead cat (not a psychocat) and buckets of stage blood. For his movies, McDonagh has broadened the thematic focus from quarreling relatives to working stiffs — thugs, that is, whose business is to turn suspects into stiffs — who form their own kind of dysfunctional family. That was the story of In Bruges, a tale of two killers (Farrell and Brendan Gleeson) on a Belgian holiday in Hell. The new film, the script for which McDonagh wrote seven years ago, could be In Bruges gone meta: more, and more bizarre, characters, in a movie that doubles back, comments on and makes fun of itself.

The one relative innocent in this L.A. vulture vita is Marty (Farrell), a screenwriter who has come up with the title for a movie — Seven Psychopaths — but no story. His actor pal Billy (Rockwell) helpfully places a want-ad calling on people who consider themselves psychopaths. That summons unusual visions of killers: one Amish, one a Buddhist monk and the third Tom Waits, petting a rabbit. Billy might also qualify. A hot-tempered type with a streak of inane self-justification, he says of one assault, “I didn’t want to break his nose. His nose just happened to be in the middle of where I was punching.”

Between acting jobs, which is always, Billy runs a scam with the older Hans (Walken) to steal the dogs of rich people and return them for reward money. Their mistake comes in filching a Shih Tzu named Bonnie from a gangster named Charlie (Harrelson), who loves only two things: his pet and killing the people who steal it. Billy and Hans should have realized the seriousness of their dognapping when they read Bonnie’s dog tag: “Return to Charles Castello or you will f—ing die.”

At one point the frazzled Marty asks, “What’re we gonna do?” and Billy and Hans chip in, “We could take on all the bad guys… maybe in a desert.” No, Marty says, “What do you think we should do in real life?” Of course, this isn’t real life; it’s a movie, as the screenwriter doesn’t know but the actor does. At first, viewers may find it hard to tell whether the movie is winking at them or closing one eye for a better, fatal aim at its victims in the theater. But as, say, Hans describes a movie scene that is soon played out on screen, it should be clear that the filmmaker, the actors and the characters — the audience, too — are all meant to be in on the same rich joke.

Offering dark fun under the broiling California sun, the movie is essentially the fanciful autobiography of any writer stuck at the onset of the creative process. McDonagh’s solution was to let the macho side of his imagination run amok, and to enlist favorite colleagues (Farrell from In Bruges, Rockwell and Walken from the Broadway version of A Behanding in Spokane) to gallop along with him. Any actors with a free day or two — Waits, Harry Dean Stanton, Olga Kurylenko, Zeljko Ivanek, Abbie Cornish, Gabourey Sidibe, plus Pitt and Stuhlbarg — were welcome to join this raffish caper. In this competition of reigning eccentrics, Rockwell is the surprise winner for his intense and acute bantam lunacy.

Small in stature but consistently entertaining, Seven Psychopaths is a vacation from consequence for the Tony- and Oscar-winning author, and an unsupervised play date for his cast of screw-loose stars.

I’ve heard so many good things about this movie. A couple of my DISH co-workers are planning to see it this weekend and they invited me. I’d love to go, but unfortunately I just don’t have time. I’m going to add it to my Blockbuster @ Home queue through my DISH account instead. As soon as it comes out on DVD it’ll show up in my mailbox. My roommate and I will have to make a movie night out of it.